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<br />...... <br />-..l <br />CJl <br />-.1 <br /> <br />In the study by Drs. Calabrese and Tuthill, a difference of 2 to 5 <br />millimeters (rom) mercury of blood pressure was found between third graders <br />with a drinking water supply of about 10 mg/L sodium and those drinking water <br />of about 102 mg/L sodium. <br /> <br />Subsequent attempts by Drs. Calabrese and Tuthill to validate these <br />results with other groups or by other methods (bottled water) have proven <br />inconclusive. Studies reported from the Netherlands did support findings of <br />slightly elevated blood pressure among schoolchildren consuming high sodium <br />water, but most other studies were either inconclusive or showed that there <br />was no effect. <br /> <br />Two areas of concern mentioned during the discussions were the use <br />of zeolite water softeners on the kitchen cold water faucet and the cooking of <br />vegetables in high sodium water, as the vegetables could absorb large amounts <br />of sodium during cooking. In most cases, avoidance of these two actions would <br />be more significant than any reduction in raw water concentration. <br /> <br />, II <br /> <br />A significant correlation between higher blood pressure and <br />increased cardiovascular disease mortality was presented at the conference. <br />The link between sodium and high blood pressure was, however, weak. <br /> <br />other conference discussions on hard versus soft water primarily <br />concluded that soft water was not harmful, but hard water contained some <br />beneficial property, possibly calcium, which reduced the ability of the body <br />to absorb trace metals and thus lowered the overall exposure to such elements <br />as cadmium and lead. <br /> <br />Additionally, while water softeners are useful in reducing pipe <br />scaling and soap usage, it was stressed by several speakers that a bypass <br />should be placed on the kitchen cold water tap, the tap most used for drinking <br />and cooking water, to maintain a certain level of hardness. <br /> <br />Other papers focused primarily on the health effects of cadmium, <br />barium, and lead in drinking water. Epidemiological studies seem to indicate <br />that barium has no effect on cardiovascular disease below a level of about 10 <br />mg/L, while cadmium and lead do have a definite adverse impact. None of these <br />elements are present in any significant concentrations in the main stem <br />reaches of the Colorado River. <br /> <br />It appears from discussions at the conference that there would not <br />be adverse ,health impacts related to present sodium or hardness levels in <br />drinking water from the Lower Colorado River. Any health effect of a <br />reduction in sodium and hardness expected from the Colorado River Salinity <br />Control Program would be negligible. <br /> <br />IV-5 <br />